DES MOINES, Iowa--Ron Paul, standing backstage before a Republican presidential debate in Spartanburg, South Carolina not long ago, was talking to Doug Wead, one of his senior advisers, about his Christian faith.

In the moments before the debate, Paul explained how his beliefs in limited government and even his opposition to the Federal Reserve had their foundations in scripture, combined with his study of the Constitution. Before he left to take the stage that night in November, Paul smiled and said to Wead, who told this story to Yahoo News, "You know, the libertarians are just baffled by me. They didn't think it was possible for someone to come this direction. A person of faith."

In stark contrast to how he campaigned four years ago, Paul has made a concerted push during this presidential campaign to emphasize how religion has shaped his policy ideas. Through public addresses, campaign advertisements and conversations with voters, Paul has engaged in an intentional effort to articulate the biblical roots of his philosophy. These efforts are most on display here in Iowa, where most Republican caucusgoers align themselves with socially conservative views, and where Paul is building what has become a robust organizational machine to connect with them. Paul has surged into second place in Iowa, according to several recent polls. The Real Clear Politics polling average for the state has Paul tied with Mitt Romney at 17 percent, behind Newt Gingrich's 30 percent.

Paul has brought several Christian conservatives onto his campaign in an ambitious effort to reach believers for his cause. Michael Heath, the campaign's Iowa director, previously worked for a New England-based group called the Christian Civic League of Maine that fought against adding sexual orientation to the state's Human Rights Act.

The national campaign has tasked Heath with leading church outreach in Iowa, where for months he has met with pastors and Christian congregations. "That's the biggest part of what I'm doing as state director," Heath told Yahoo News after a day of knocking on church doors with campaign literature. "Going to churches with a message in support of Dr. Paul's campaign that is very much faith-based and is also rooted in his commitment to a constitutionally defined limited federal government."

'The most socially conservative candidate'?

During his years in public office, Paul branded himself more as a "constitutional conservative" than a crusader against gay marriage and abortion. Most political observers know him more for his youthful fan base of passionate and, occasionally, rowdy supporters and his earnest defense of drug legalization. But the latest Iowa Poll, conducted for the Des Moines Register at the end of November, found that 17 percent of likely Republican caucusgoers said they thought Paul was "the most socially conservative" candidate in the race, second only to Michele Bachmann with 27 percent. (The margin of error was plus or minus 4.9 percentage points.)

Only 1 in 10 likely caucusgoers in the poll said Newt Gingrich was the most socially conservative candidate, and former Massachusetts Gov. Mitt Romney fared even worse with just 8 percent. The same poll found that 64 percent of Iowa's likely voters considered themselves to be "very" or "mostly" conservative on gay marriage and abortion. In June, a survey conducted by the same group found that 58 percent of likely caucusgoers said a candidate's support for civil unions for gay and lesbian couples would be considered a "deal killer."

Paul sides with social conservatives on most issues: He believes that marriage should be defined as being between only one man and one woman and he does not think the federal government should guarantee women the right to have an abortion, a position influenced by his decades as an obstetrician who delivered thousands of babies. In public speeches, Paul often articulates a biblical foundation for his economic policies, framing capitalism as the moral giant among all other economic systems.

Prominent religious conservatives in Iowa, however, object that Paul does not apply his beliefs at the national level. Paul does not support a constitutional amendment to ban abortion, and he opposes a constitutional amendment to ban gay marriage. He thinks both issues should be left up to the states.

Bob Vander Plaats, the chief executive officer of an Iowa-based conservative advocacy group called the Family Leader, said that while he likes Paul personally, he sees little reason to support him. Vander Plaats, a three-time gubernatorial candidate, was the Iowa chairman for Mike Huckabee's (victorious in Iowa) presidential campaign.

Paul joined six other candidates at a Thanksgiving forum held by the Family Leader in Des Moines, where he took a lonely stand by arguing against legislating morality through the power of the federal government. "The role of government isn't to mold society and mold people," Paul said. "The role of government is to preserve liberty."

By the next week, the Family Leader removed Paul's name from the list of candidates that it was considering endorsing.

"Although we believe he's right on the sanctity of human life, we believe he's wrong when it's left to state's rights issues," Vander Plaats told Yahoo News this week during an interview in his office in Des Moines. "We believe he's right in his belief in one woman one man marriage. We believe he's wrong where he says the states should have nothing to do with it. To us this is a morality issue. So the reason you don't have slavery in Alabama and not slavery in Iowa is because slavery is wrong. And we believe abortion is wrong. We don't believe it should be left up to the states. And the same way with marriage."

Steve Scheffler, the leader of another influential group in the state, the Iowa Faith and Freedom Coalition, has similar concerns about Paul. "I have no doubt that his core is that he's pro-life, but he probably makes it a little challenging when he doesn't support a constitutional amendment on life," Scheffler told Yahoo News. "I don't feel a lot social conservatives are gravitating toward him. He makes it hard for people to support him."

'Does it take some explanation? Yes. Can it be done? Yes.'

These leading voices in Iowa have not stopped Paul from trying to appeal to the state's socially conservative voters.

Doug Wead, a born-again Christian who worked for George H.W. Bush and whom Paul has tasked with rallying Christians nationally for his candidacy, has helped Paul to craft a message tailored specifically to religious conservatives.

Paul quotes Proverbs 22:7--"the borrower is servant to the lender"--when discussing his Israel policy. He cites Deuteronomy 25:15, which commands a system of "honest weights and measures" to argue for sound monetary policy. And he often tells the story of how Jesus drove the money lenders out of the temple to illustrate his outrage over his belief that the Federal Reserve dilutes the value of currency.

Explaining Paul's philosophy of liberty to evangelical voters comes with challenges, Wead conceded. "It is hard. But once they get it, they get it they see the power of it," Wead said. "Does it take some explanation? Yes. Can it be done? Yes, and it's been done incrementally in Iowa with great success."

Paul's campaign has also targeted much of its state-based advertising toward Iowa's socially conservative voters, and Paul has written personal letters to key pastors in the state.

In what is perhaps his most emotionally stirring ad, "Life," which has played throughout the state and received more than 175,000 hits on YouTube, Paul describes in detail his experience walking into a hospital room where doctors administered a late-term abortion. "Unless we resolve this," Paul says, "and understand that life is precious and we must protect life, we can't protect liberty."

Paul's efforts to reach these voters are not new, his campaign aides say. He has worked for years to gain access to an inner circle of Iowa-based religious conservatives. David Lane, a California-based evangelical political activist, has organized off-the-record policy briefings with pastors across the country since the 1990s. These invitation-only meetings give local pastors an opportunity to meet Republican candidates and, until recently, Paul was never invited.

Lane, who helped organize Rick Perry's August prayer rally in Houston, received multiple requests from Wead to let Paul speak to the pastors. After two years of urging from Wead, Lane agreed to allow Paul to come to a meeting of 400 pastors on Nov. 14 at the Marriott hotel in Des Moines. Paul canceled campaign events in New Hampshire and flew straight to Des Moines, where he joined Gingrich and Perry and delivered his regular speech about how his political beliefs are rooted in the teachings of scripture.

The reactions from the pastors, who were already skeptical of Paul, were mixed. "The evangelical constituency has not been somebody that Ron Paul, as far as I can tell, has really reached out to," Lane told Yahoo News. "Rick Perry and Newt Gingrich are much more comfortable speaking to that constituency."

When Paul was on stage that night, a man who claimed to work for the Paul campaign was caught slipping anti-Gingrich flyers under the doors of the pastors' hotel rooms. The campaign says the man is not involved with the candidate in any capacity--the flyers said they were printed by a mysterious group called "Iowans for Christian Leaders in Government"--but the insinuation couldn't have helped Paul, who already was perceived as an outsider out at the conference.

Regardless, Paul's team saw having access to Lane's network of Iowa religious leaders as a major breakthrough.

"The bottom line," Wead said, "is that we are now battling for the evangelical vote too."

Holly Bailey contributed to this report.

This story is part of a series of articles on the politics of Iowa, leading up to Saturday's Republican presidential debate in Des Moines, sponsored by Yahoo News and ABC News. Come to Yahoo! at 9 p.m. ET on Saturday to watch the debate, to provide real-time feedback, and to watch and read live coverage and analysis.